This allows the arch code to reset the page tables to cached access when freeing a dma coherent allocation that was set to uncached using arch_dma_set_uncached. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- arch/Kconfig | 7 +++++++ include/linux/dma-noncoherent.h | 1 + kernel/dma/direct.c | 2 ++ 3 files changed, 10 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index 090cfe0c82a7..c26302f90c96 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -255,6 +255,13 @@ config ARCH_HAS_SET_DIRECT_MAP config ARCH_HAS_DMA_SET_UNCACHED bool +# +# Select if the architectures provides the arch_dma_clear_uncached symbol +# to undo an in-place page table remap for uncached access. +# +config ARCH_HAS_DMA_CLEAR_UNCACHED + bool + # Select if arch init_task must go in the __init_task_data section config ARCH_TASK_STRUCT_ON_STACK bool diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h index 1a4039506673..b59f1b6be3e9 100644 --- a/include/linux/dma-noncoherent.h +++ b/include/linux/dma-noncoherent.h @@ -109,5 +109,6 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size) #endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */ void *arch_dma_set_uncached(void *addr, size_t size); +void arch_dma_clear_uncached(void *addr, size_t size); #endif /* _LINUX_DMA_NONCOHERENT_H */ diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index f01a8191fd59..a8560052a915 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -219,6 +219,8 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) vunmap(cpu_addr); + else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED)) + arch_dma_clear_uncached(cpu_addr, size); dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size); } -- 2.24.1
